Hearing aids are very small and delicate devices and comprise many electronic and metallic components contained in a housing small enough to fit in the ear canal of a human or behind the outer ear. The many electronic and metallic components in combination with the small size of the hearing aid housing impose high design constraints on radio frequency antennas to be used in hearing aids with wireless communication capabilities.
Conventionally, antennas in hearing aids have been used for receiving radio broadcasts or commands from a remote control. Typically, such antennas are designed to fit in the hearing aid housing without special concern with relation to the efficiency of the antenna.
A variety of hearing aids are known, including so called behind-the-ear hearing aids, in-the-ear hearing aids, receiver-in-the-ear hearing aids, etc. Some hearing aids have been designed with a cable or a sound tube connecting hearing aid elements positioned behind the ear of a user with hearing aid elements position in the ear of a user. It has been suggested to use such cables or sound tubes for accommodating antenna elements. For example in U.S. Pat. No. 8,300,863, a hearing aid having a cable or a sound tube connecting the hearing aid to a receiver in the ear of a user or to a speaker in the ear, respectively, is configured for wireless communication via an antenna, and the cable or sound tube comprises a conducting element forming at least part of the antenna. Furthermore, EP 2 088 804 discloses a hearing aid having a cable comprising one or more conductors for connecting a hearing aid housing with a transducer in the ear of a user. To enable wireless communication, a wireless transceiver in the hearing aid may be connected to one of the transducer cables to provide a monopole antenna, or the wireless transceiver may be connected to two transducer cables to provide a dipole antenna for the wireless transceiver.